Technically, you should stop getting calls as soon as the bankruptcy court enters the automatic stay. An automatic stay is an order entered by the court which requires collection efforts against you to cease, and the order is entered immediately when the bankruptcy court receives your petition for bankruptcy. However, creditors can ask the bankruptcy court to lift the automatic stay so that they may pursue collection efforts. Whether or not the court will lift the automatic stay depends on the facts of your individual case.
Creditors who persist in their attempts to collect debts without the permission of the bankruptcy court may be sanctioned and subject to penalties. However, the automatic stay has limits that also protect creditors. For example, the stay may be terminated in situations that indicate a series of bad faith and abusive bankruptcy filings. Evictions are not automatically stayed, and alimony and child support do not stop when you file for bankruptcy.
For more information, see: 11 U.S.C. § 362 (2015); The Bankruptcy Abuse Prevention and Consumer Protection Act of 2005, 109 P.L. 8 § 305-315 (2005); National Consumer Law Center, Surviving Debt: A Guide for Consumers (3rd ed. 1999).